Assessment of tree diversity and above-ground biomass in coffee agroforest dominated tropical landscape of India’s Central Western Ghats

Abstract

The purpose of this study was to quantify the changes in tree diversity and above-ground biomass associated with six land-use types in Kodagu district of India’s Western Ghats. We collected data on species richness, composition and above-ground biomass (AGB) of trees, shrubs and herbs from 96 sample plots of 0.1 ha. Totals of 83 species from 26 families were recorded across the land-uses. Tree species richness, diversity and composition were significantly higher in evergreen forest (EGF) than in other land-uses. Similarly, stem density and basal area were greater in EGF compared to other land-uses. Detrended correspondence analysis (DCA) yielded three distinct groups along the land-use intensities and rainfall gradient on the first and second axes, respectively. The first DCA axis accounted for 45% and second axis for 35% of the total variation in species composition. Together the first two axes accounted for over 2/3 of the variation in species composition across land-use types. Across the land-uses, AGB ranged from 58.6 Mg ha−1 in rubber plantation to 327.3 Mg ha−1 in evergreen forest. Our results showed that species diversity and AGB were negatively impacted by the land-use changes. We found that coffee agroforests resembled natural forest and mixed species plantation in terms of tree diversity and biomass production, suggesting that traditional coffee farms can help to protect tree species, sustain smallholder production and offer opportunities for conservation of biodiversity and climate change mitigation.